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Infocom. 4. ea 2013. szept. 30.1 Infokommunikációs rendszerek – Infocommunication Systems Lecture 4. előadás Kódolás, nyalábolás, kapcsolás Coding, multiplexing,

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Presentation on theme: "Infocom. 4. ea 2013. szept. 30.1 Infokommunikációs rendszerek – Infocommunication Systems Lecture 4. előadás Kódolás, nyalábolás, kapcsolás Coding, multiplexing,"— Presentation transcript:

1 Infocom. 4. ea 2013. szept. 30.1 Infokommunikációs rendszerek – Infocommunication Systems Lecture 4. előadás Kódolás, nyalábolás, kapcsolás Coding, multiplexing, switching Takács György

2 Infocom. 4. ea 2013. szept. 30.2 Where we are now in study (tele-, info-) communications systems? Networks are working systems of terminals, nodes and links The basic technologies in links (wireline and wireless) have been discussed Node functions (multiplexing, switching, signalling, demultiplexing) will be discussed today

3 Infocom. 4. ea 2013. szept. 30.3

4 4

5 5 Analog modulation systems- (AM) Amplitude modulation The momentary amplitude of the carrier is proportional to the momentary amplitude of the modulating signal

6 Infocom. 4. ea 2013. szept. 30.6 Analog modulation systems- (AM)

7 Infocom. 4. ea 2013. szept. 30.7 The spectrum of the AM in the case of discrete f m modulation frequency

8 Infocom. 4. ea 2013. szept. 30.8 Frequency modulation systems- (FM) The momentary frequency of the carrier is proportional to the momentary amplitude of the modulating signal

9 Infocom. 4. ea 2013. szept. 30.9 Frequency modulation systems- (FM)

10 Infocom. 4. ea 2013. szept. 30.10 The spectrum of FM modulated signal in the case of discrete f m modulation frequency

11 Infocom. 4. ea 2013. szept. 30.11 Digital modulation methods – Amplitude Shift Keying (ASK)

12 Infocom. 4. ea 2013. szept. 30.12 Digital modulation methods – Binary Phase Shift Keying (BPSK)

13 Generation of BPSK Infocom. 4. ea 2013. szept. 30.13 x  ~ Carrier signal BPSK t 1 0 0 1 +1

14 Infocom. 4. ea 2013. szept. 30.14 Digital modulation methods – Constellation Diagram / BPSK

15 Infocom. 4. ea 2013. szept. 30.15 Eye diagram as a basis for demodulation of BPSK signal Received BPSK signal x Carrier signal comparator 1,0,1,0 ∫ Eye diagram

16 Infocom. 4. ea 2013. szept. 30.16 Digital modulation methods –Qadrature Phase Shift Keying (QPSK) Two carriers: sine wave (Q) and cosine wave (I) The modulated signal is the sum of the two components One symbol is two bits

17 Infocom. 4. ea 2013. szept. 30.17 Digital modulation methods –Qadrature Phase Shift Keying (QPSK)

18 Infocom. 4. ea 2013. szept. 30.18 Digital modulation methods –Qadrature Phase Shift Keying (QPSK)

19 Infocom. 4. ea 2013. szept. 30.19 Digital modulation methods –Qadrature Phase Shift Keying (QPSK) 1

20 Infocom. 4. ea 2013. szept. 30.20 Digital modulation methods –Qadrature Amplitude Modulation (QAM) Two carriers: sine wave (Q) and cosine wave (I) The modulated signal is the sum of the two components Different amplitude and differnt phase values for one symbol 16QAM means: one symbol is four bits

21 Infocom. 4. ea 2013. szept. 30.21 Digital modulation methods –Qadrature Amplitude Modulation (16QAM)

22 Infocom. 4. ea 2013. szept. 30.22 Digital modulation methods –Qadrature Amplitude Modulation (16QAM)

23 Infocom. 4. ea 2013. szept. 30.23 Digital modulation methods –Qadrature Amplitude Modulation with channel noise

24 Infocom. 4. ea 2013. szept. 30.24 Why to use sophisticated modulations -- like QAM? To put more bits into the standard medium –twisted pair cable –ADSL, Gigabit Ethernet, –coaxial cable – digital TV, HDTV, INTERNET, –Radio – GSM, satellite TV and radio program broadcasting Efficient use of spectum (the radio spectrum is a limited resource)

25 Bit error rate as a function of signal to noise ratio using BPSK modulation Infocom. 4. ea 2013. szept. 30.25

26 Channel capacity as a function of signal to ratio at different modulation system. The reference is the BPSK Infocom. 4. ea 2013. szept. 30.26

27 Infocom. 4. ea 2013. szept. 30.27 Multiplexing vs. switching City ACity B 10 5 10 3 Trunks for active calls only

28 Infocom. 4. ea 2013. szept. 30.28 Multiplexing principles To reduce transmission costs To utilize higher bandwidth „Framing” and „packing” of information TDM -- Time Division Multiplexing FDM -- Frequency Division Multiplexing CDMA -- Code Division Multiple Access WDM -- Wavelength Division Multiplexing Mixed

29 Infocom. 4. ea 2013. szept. 30.29 TDM principles I. PCM frame 4.50 ábra (Pulse Code Modulation) 125 µs

30 Infocom. 4. ea 2013. szept. 30.30 TDM principles II. PDH hierarchy 4.51 ábra Plesiochronous Digital Hierarchy

31 Infocom. 4. ea 2013. szept. 30.31 TDM principles III. PDH hierarchy 4.51 ábra

32 Infocom. 4. ea 2013. szept. 30.32 SDH hierarchy SDH – Synchronous Digital Hierarchy VC – Virtual Container (multiplexing level) STM-N Synchronous Transport Modules (line signal level) POH – path overhead (control and supervisory information) POH+Payload=VC A number of VCs can packaged into a larger VC

33 Infocom. 4. ea 2013. szept. 30.33 Transport modules RSOH – Regenerator Section Overhead MSOH – Multiplexer Section Overhead AU Pointer – Administrative Unit Pointer (specifies where the payload starts) Duration of STM-1 module is 125 µs

34 Infocom. 4. ea 2013. szept. 30.34 General Transport Module 4.56. ábra

35 Infocom. 4. ea 2013. szept. 30.35

36 Infocom. 4. ea 2013. szept. 30.36

37 Infocom. 4. ea 2013. szept. 30.37 SDH Network elements DXC – Digital Cross Connect ADM – Add-drop Multiplexer TM – Terminal multiplexer

38 Infocom. 4. ea 2013. szept. 30.38 Example of a physical network

39 Infocom. 4. ea 2013. szept. 30.39 FDM principles

40 Infocom. 4. ea 2013. szept. 30.40 TDM/FDM channel architecture as used in GSM

41 Infocom. 4. ea 2013. szept. 30.41 FDM in Cable TV network (US Standard)

42 Infocom. 4. ea 2013. szept. 30.42 Variable bit-rate data transfer within TDM time- slots

43 Infocom. 4. ea 2013. szept. 30.43 The Spread Spectrum Concept

44 Infocom. 4. ea 2013. szept. 30.44 General Model of Spread Spectrum Digital Communication System

45 Infocom. 4. ea 2013. szept. 30.45 Frequency_Hopping Spread Spectrum FHSS

46 Infocom. 4. ea 2013. szept. 30.46 FHSS A number of channels are allocated for FH The transmitter operates in one channel at a time for fixed time interval (Tc) During that interval, some number of bits or a fraction of a bit are transmitted (signal elements) The time interval of signal elements Ts The sequence of the channels used is dictated by spreading code Both transmitter and receiver use the same code to tune into a sequence of channels in synchronisation

47 Infocom. 4. ea 2013. szept. 30.47 Transmitter of the FHSS System

48 Infocom. 4. ea 2013. szept. 30.48 Receiver of the FHSS System

49 Infocom. 4. ea 2013. szept. 30.49 Slow FHSS using Multi Frequency Shift Keying Tc>Ts (in this case 4 subfrequencies for 2 bits)

50 Infocom. 4. ea 2013. szept. 30.50 Fast FHSS using Multi Frequency Shift Keying Tc { "@context": "http://schema.org", "@type": "ImageObject", "contentUrl": "http://images.slideplayer.com/3991097/12/slides/slide_49.jpg", "name": "Infocom.4. ea 2013. szept.", "description": "30.50 Fast FHSS using Multi Frequency Shift Keying Tc

51 Infocom. 4. ea 2013. szept. 30.51 Example of Direct Sequence Spread Spectrum DSSS

52 Infocom. 4. ea 2013. szept. 30.52 DSSS system Transmitter

53 Infocom. 4. ea 2013. szept. 30.53 DSSS system Transmitter

54 Infocom. 4. ea 2013. szept. 30.54 Comparison of FDM –TDM -- CDM TDMAFDMA

55 Infocom. 4. ea 2013. szept. 30.55 Principle of WDM

56 Infocom. 4. ea 2013. szept. 30.56 Principle of WDM

57 Infocom. 4. ea 2013. szept. 30.57 Switching techniques in public networks

58 Infocom. 4. ea 2013. szept. 30.58 The Group Switch interconnects incoming and outgoing time slots

59 Infocom. 4. ea 2013. szept. 30.59 Time and space switches

60 Infocom. 4. ea 2013. szept. 30.60 The principle of TST switching

61 Infocom. 4. ea 2013. szept. 30.61 Group switch with 512 multiple position

62 Infocom. 4. ea 2013. szept. 30.62 Connections to the local exchange

63 Infocom. 4. ea 2013. szept. 30.63 Node for packet switching

64 Infocom. 4. ea 2013. szept. 30.64 Packet node structure

65 Infocom. 4. ea 2013. szept. 30.65 Connection oriented transfer phases: Connection setup (setup packet with complete address, Logical Channel Number stored in each node Data transmission (only LCN in the header) Release Connectionless transport: Destination address in the header Path selection in the nodes Different packets have different delay The order of received packets has no guarantee

66 Infocom. 4. ea 2013. szept. 30.66 ATM cell switching principle Fixed cell (packet) length – 53 bytes 5 octets header, 48 octet payload

67 Infocom. 4. ea 2013. szept. 30.67 Why connection oriented packet switching? Connectionless – only best effort quality (www = world wide waiting) Connection oriented – QoS guarantee is possible Quality measures: delay, jitter, packet loss.

68 Infocom. 4. ea 2013. szept. 30.68 Content of ATM cell header

69 Infocom. 4. ea 2013. szept. 30.69 Segmentation and multiplexing of different Services in cell based systems

70 Infocom. 4. ea 2013. szept. 30.70 The principle of ATM switching

71 Infocom. 4. ea 2013. szept. 30.71 VP (Virtual Path „coarse level addressing”) and VC (Virtual Channel „fine level addressing”)

72 Infocom. 4. ea 2013. szept. 30.72 The structure of the ATM switch

73 Infocom. 4. ea 2013. szept. 30.73 Signalling principles in circuit switching

74 Infocom. 4. ea 2013. szept. 30.74 Signalling flow in a telephone call

75 Infocom. 4. ea 2013. szept. 30.75 Signalling for distributed supplementary services or a mobile telephone call

76 Infocom. 4. ea 2013. szept. 30.76 Signalling in packet switched networks

77 Infocom. 4. ea 2013. szept. 30.77 Principles of Common Channel Signalling CCS

78 Infocom. 4. ea 2013. szept. 30.78

79 Photonic Fibre Switches In free-space devices, the light is focused from the input fibre, deflected by a micro-mirror (typically several times) and finally launched into the output fibre. The Micro- Electro-Mechanical Systems (MEMS) technology is mature and can produce switch matrices with up to hundreds of input and output ports (128x128 or 256x256), low insertion loss (IL), very low cross talk, low power consumption, millisecond switching speed, and broadband operation. The mirrors can typically be controlled electro-magnetically, electro-statically or by piezoelectric actuators. Infocom. 4. ea 2013. szept. 30.79

80 Operational principle and example of 3D MEMS array Infocom. 4. ea 2013. szept. 30.80 collimator


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